The present invention is for a backwashing filter basket for an overflow structure for a retention pond or the like. The backwashing filter basket is attached to the overflow structure over the outlet weir so that floating debris, such as trash, leaves, grass clippings, tree stems and the like, is captured by the filter basket while sand, gravel and non-floating materials pass through the filter screen. The backwashing filter is backwashed by the falling rain.
An overflow structure is in retention ponds to prevent storm water from leaving the retention pond to allow the water to soak into the ground in the pond until the water level reaches a maximum height. The control or overflow structure has a cutout area in one side thereof forming a weir to allow the gradual overflow of the retention pond water through the structure and into the area storm water runoff. The retention pond however collects floating grass clippings, leaves, debris and other floating matter while sand, gravel and non-floating matter settles in the pond. Non-floating matter settles in the retention pond or in the control structure while the floating matter is allowed to flow into the control overflow structure and ultimately over the overflow weir where it is captured in the storm water system screens placed over the overflow weir.
These screens work well except they have a tendency to get stopped up with floating trash which reduces and blocks the flow of the overflow structure. It is desirable to remove floating organic debris from the water collected within a retention pond and overflow structure before it enters into a storm water runoff.
In my prior U.S. Pat. No. 7,270,747 a storm water drain system has a nutrient separating filter basket installed within the storm water drain pipe system to receive storm water runoff therethrough and to collect organic materials, such as grass clippings, leaves and tree stems, and to hold these organic materials above the water level in the storm water drain system to prevent their decay and release of soluble nutrients into the water. In this prior patent, water enters the housing inlet and is directed by an inlet feed chute into the basket and through the screen side and bottom while a filter bottom collects the organic debris therein.
The present invention is directed towards a filter or filter basket for an overflow structure for a retention pond or the like which is automatically cleaned by falling rain or water.